Novel microstructure and large magnetocaloric effect in La 2 Fe 11 Si 2 magnetic refrigerant

A study of the microstructure and magnetocaloric effect in bulk La2Fe11Si2, as an off-stoichiometric NaZn13-type La(Fe,Si)13 composition, was carried out. The microstructure and phase constitution strongly rely upon heat treatment processing, especially on annealing temperature. Upon annealing at 1423 K, a unique morphology containing granular-like La(Fe,Si)13 grains with a high fraction of ~80 vol.%, surrounded by Cr5B3-type La5Si3 phase was observed. A large entropy change of 14.5 J/kg K in 2 T was achieved in this bulk sample after annealing for a relatively short time (e.g. 24 h). In addition, the bulk sample also exhibits pronounced first-order magnetic transition behavior with zero thermal and magnetic hysteresis. The syntheses of bulk La2Fe11Si2 alloy with good magnetocaloric performance by simplified preparation process are encouraging for future development of LaFe-based magnetocaloric alloys as a magnetic refrigerant for magnetic cooling system applications.